The present invention relates generally to an internal combustion engine, and more particularly to an apparatus and method for controlling a fuel injector assembly of an internal combustion engine during cold operation thereof.
During operation of an internal combustion engine, it is desirable to control the formation and emission of certain gases, such as the oxides of nitrogen (NOx). One method of achieving this result is the use of water fuel emulsions. A water fuel emulsion is a certain type of mixture of a fuel, such as diesel fuel, and water. Additionally, a number of additives may also be included in the mixture to keep the fuel and water emulsified (i.e. the fuel and water form an emulsion). Use of such water fuel emulsions reduces the amount of NOx produced during operation of the internal combustion engine. In particular, NOx is produced when nitrogen and oxygen are combined at the high temperatures associated with combustion. Use of water fuel emulsions in lieu of standard diesel fuel reduces the combustion temperatures associated with the internal combustion engine thereby reducing NOx production during operation thereof.
However, use of water fuel emulsions has a number of drawbacks associated therewith. For example, during cold starting or cold running conditions, internal combustion engines fueled by water fuel emulsions may have a tendency to misfire in one or more of the engine""s cylinders thereby producing undesirable smoke and exhaust odors. In particular, water fuel emulsions typically have lower cetane levels relative to standard diesel fuel. Such lower cetene levels may undesirably reduce the compression ignition quality of the internal combustion engine thereby potentially causing the engine to misfire during cold starting or cold running conditions. Such misfiring is typically reduced, if not completely eliminated, when the internal combustion engine reaches the normal operating temperature associated therewith.
What is needed therefore is an apparatus and method for controlling a fuel injector assembly of an internal combustion engine that is fueled by a water fuel emulsion which overcomes one or more of the above-mentioned drawbacks.
In accordance with a first embodiment of the present invention, there is provided a method of controlling a fuel injector assembly of an internal combustion engine. The internal combustion engine has a first cylinder. The fuel injector assembly has a fuel injector which is operatively associated with the first cylinder. The method includes the step of injecting fuel into the first cylinder with the fuel injector during a first engine cycle. The method further includes the step of sensing a combustion-absent condition in the first cylinder during the first engine cycle and generating a combustion-absent control signal in response thereto. The method also includes the step of preventing fuel from being injected into the first cylinder with the fuel injector during a second engine cycle if the combustion-absent control signal is generated in the combustion-absent sensing step.
In accordance with a second embodiment of the present invention, there is provided an apparatus for controlling a fuel injector assembly of an internal combustion engine. The apparatus includes a first cylinder, and a combustion sensor for sensing (i) a combustion-absent condition in the first cylinder, and (ii) a combustion-present condition in the first cylinder. The apparatus also includes an engine control module which (i) generates a combustion-absent control signal when the combustion sensor senses the combustion-absent condition in the first cylinder during a first engine cycle, and (ii) generates a combustion-present control signal when the combustion sensor senses the combustion-present condition in the first cylinder during the first engine cycle. The apparatus further includes a fuel injector which (i) injects fuel into the first cylinder during a second engine cycle in response to generation of the combustion-present control signal, and (ii) avoids injecting fuel into the first cylinder during the second engine cycle in response to generation of the combustion-absent control signal.
In accordance with a third embodiment of the present invention, there is provided a method of controlling a fuel injector assembly of an internal combustion engine. The internal combustion engine has a first cylinder. The fuel injector assembly has a fuel injector which is operatively associated with the first cylinder. The method includes the step of injecting fuel into the first cylinder with the fuel injector. The method also includes the step of sensing a combustion-absent condition in the first cylinder and generating a combustion-absent control signal in response thereto. The method further includes the step of preventing fuel from being injected into the first cylinder with the fuel injector for a predetermined period of time after generation of the combustion-absent control signal.